“The five men arrested on suspicion of explosives offences have now been released without charge.

“Following a thorough investigation we are satisfied that there are no grounds with which to charge the men with any offences and would like to reassure local people that there are no public safety concerns connected with this matter.”

Northumbria Police said the investigation had been referred to Counter Terrorism Policing North East due to their “specialist knowledge when it comes to enquiries of this nature”.

A force spokesman said on Thursday: “We recognise that people may have concerns about an investigation of this kind but we want to reassure the public that there is no immediate threat to their safety.

“Officers will be on patrol across the West End as normal and if anyone has any concerns we would encourage you to speak to those officers.”